The present invention relates to an electronic device and a defect repair method thereof. More specifically, it relates to a method of repairing failure points of an electronic device to have a perfect function and a repaired electronic device.
An Extended Video Graphics Array (XGA) Liquid Crystal Display (LCD) having 1024xc3x97768 pixels has approximately 2.36 million pixels. Each pixel is driven by a Thin Film Transistor (TFT). It is very difficult to manufacture sub-pixels without any defects in the manufacturing process of such LCD. For this reason, a limited number of point, region or location defects are ordinarily allowed.
There is a case where one defective sub-pixel can cause a malfunction, which causes a picture element to generate different colors or bright points appear when a black color should appear. In this case, an entirely different color from peripheral colors appear or only one point shines in white color when filling all of the display completely with black color, which leads to low contrast of the screen. Consequently, point defects appear on the display. One of the methods for repairing point defects is disclosed in Japanese Laid-Open Patent Publication No. 6-11675, for example. The method is to change bright point defects to dark point defects by covering the bright point defective portion with black color or leaving an ink of a heat transfer sheet on the bright point defective portion. Or, defects are repaired by a self-leak method which is a fake repair method to make dark/bright points to be inconspicuous dots. Either of these methods were not repair solutions to remove defects because these methods only make dark/bright points to be inconspicuous dots. It was unavoidable that a remarkable yield loss occurred when we addressed severe requirements from customers such as xe2x80x9cPoint defect freexe2x80x9d.
The Japanese Laid-Open Patent Publication No. 9-230128 discloses a method that a defective filter is removed with a YAG (Yttrium Aluminum Garnet) laser beam and then the colored layer is transferred to the portion where the filter previously existed. Further, the Japanese Laid-Open Patent Publication No. 7-253583 and No. 8-150487 or the like disclose repair methods for defective conductor sections or insulator sections. Such methods are effective for removing defects. These methods were not, however, applicable to such materials as semiconductor layers because materials free of discoloring and deterioration were exclusively used even when being melted by heating. That was resulted from the need for temporally melting the colored layer and the conductors or the like using a semiconductor laser beam. Furthermore, it was impossible to repair a thin film comprising 2 layers or more simultaneously.
It is an object of the present invention to provide a method of repairing a failed point, region, location or pixel to have a perfect function when a semiconductor device including an LCD or other electronic device has defects.
It is another object of the present invention to transfer a single or multi-layer film to the other portion with its characteristics unchanged.
In accordance with the present invention, an electronic device is described comprising a substrate; a plurality of thin films laminated on the substrate and part of thin films are formed on a predetermined circuit pattern, wherein a transfer film for repairing a defect is fitted into a recess where the low layers of the thin films on the junction surface are exposed by engraving the defective points of the predetermined circuit pattern. It is difficult to remove point defects completely in highly integrated elementsxc2x7 xc2x7 such as an LCD. The defective points are removed to plant normal portions on a recess, which leads to removal of the point defects. Then, a thin film free of defects and a transfer film having an element configuration are fitted into the recess. Consequently, electric conductivity is secured on a point of circuit open by the transfer film fitted onto it. When the transfer film has an element configuration, the recess, where the transfer film is fitted into, acts as a regular element.
The present invention further provides a method of repairing a defective portion included in an electronic device in which a plurality of thin films are laminated on a substrate and part of thin films are formed on an arbitrary circuit pattern, comprising the steps of removing the thin films covering the defective portion and its surrounding portion to form a recess and exposing the lower layers of the thin films; and fitting a transfer film into the recess to attach the transfer film onto the exposed thin films. Using this defect repair method, a defective portion is firstly removed to form a recess and then a transfer film composed of a single or multi layers is transferred to the recess formed in a solid state without being melted, that is, the transfer film is fitted into the recess. Accordingly, even in the case of the transfer film composed of multi-layers, the defective portion of the electronic device is supposed to be mended to have an almost perfect function with functions and configuration undamaged. An electronic device free of point defects can be obtained by repairing all point defects.
The present invention further provides a defect repair apparatus comprising an ultrashort pulse laser generator for adjustably generating an ultrashort pulse laser;
a flexible mask pattern generator for forming an ultra short pulse laser applied by the ultrashort pulse laser generator into a predetermined shape; an optical system for converging the ultrashort pulse laser beam;
a first stage for positioning an electronic device to be repaired thereon;
a second stage for positioning a target plate thereon; and
a retention apparatus for maintaining a predetermined gap between the electronic device placed on the first stage and the target plate placed on the second stage. This defect repair apparatus particularly has the first stage where the electronic device is mounted on and the second stage for placing the target plate to perform easy positioning between the micromachined electronic device and the target plate. The electronic device and the target plate are maintained at a predetermined gap by applying proper pressure onto the first and the second stages positioned. This allows a transfer of the transfer film to the recess without any displacement and any damage.